Space heating hot-air furnace for house trailers and the like



Jan. 13, 1953 E. E. LITTLE 2,@25,l50

SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE Filed Feb.23, 1949 Y 5 Sheets-Sheet l i g f i i l I 1 M B i 46 4 ii /2 if Mi Ii 4l l 5:

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22 9 /0 20 23 Juventor I 3? I 5/4/0045 L/ff/e 8g Hi W. HIIIH HIHIHHIHL 445 Gttomegs Jan. 13, 1953 E. E. LITTLE SPACE HEATING HOT-AIR FURNACE FORHOUSE TRAILERS AND THE LIKE 5 Sheets-Sheet 2 Filed Feb. 23, 1949Zhwentor f7/liaac/ 51/2 attorneys Jan. 13, 1953 Filed Feb. 23, 1949 E.E. LITTLE SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE3 Sheets-Sheet 3 Zhwentor (Ittomegs Patented Jan. 13, 1953 SPACE HEATINGHOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE Ellwood E. Little,Wichita, Kans., assignor to The Coleman Company, Inc., Wichita, Kans., acorporation of Kansas Application February 23, 1949, Serial No. 77,796

This invention relates to space heaters which heat by convection withthe warmed air being used as the circulating medium and which areparticularly adapted for heating small spaces such as the interior ofhouse trailers.

It is well known that house trailers are difficult to heat because theyare of relatively small cubic content and have low ceilings.Consequently as in all warm air space heating, the air tends tostratify, that is, the air from the heater expands and being lighter,collects at the ceiling and the cool air being heavier, settles to thefloor. Thus, the heads of the occupants are in an exceptionally highheat zone while the feet are in a zone too cool for comfort. Thetemperature differential is often from 15 to 20 and this unhealthycondition of cold feet and overheated heads is universal in housetrailers of today. This unhealthy condition is aggravated by thebox-like structures of such trailers with the floor, roof and sides allexposed to outside -temperatures. Another disadvantage is that when theheaters are operated at suflicient- 1y high burning rate to supply therequired heat in cold weather, they may become overheated and are likelyto cause fire in the relatively limited space in which the heaters mustbe installed.

It is, therefore, the principal object of the present invention tocreate a substantially uniform temperature throughout all portions ofthe house trailer by providing a gravity flow air circulating heaterwith a power air circulator which when in operation will produce areverse circulation of the major air flow by continuously drawing offthe warm air that collects at the ceiling and forcing the air downwardlythrough the heater for added heat and then delivering the air into thecooler air at the floor. In this manner the differential temperatures inthe living' space are nearly eliminated as the entire mass of air iscaused to be blended and uniformly heated.

It is also an object of the invention to provide a heater which willoperate successfullyunder natural gravity flow circulation to deliver alarge A volume of warm air at the ceiling which falls to the floor asrapidly as the cooler air below is drawn off through the heater unitwhereby ample heat is provided when electric current is not availablefor operating the forced air circulator. It is a further object of theinvention to provide the power air circulator with means for bringing ina controlled portion of the air from outside of the space being heatedso as to furnish an oxygen content for healthful brea-thing and goodventilation. without dangerous drafts of cold air and to reduce therelative humidity which prevents sweating of walls and frosted windows.

Further objects of the invention are to pro- 8 Claims. (01. 126-110)vide a structure which requires no manual or automatic controls whenshifting from forced air circulation to natural gravity circulation asin the case of a current interruption or when the heater is startedwithout forced circulation; and to provide a heater structure whichoperates safely and efficiently whether as an upfiow natural draftheater or a forced air flow heater when the built-in power circulator isenergized.

Another object of the invention is to provide for operation of the aircirculator in connection with a cooling unit when there is no fire inthe heater, that is, the hot interior air caused. by sun exposure in theday time may be eliminated by forcing the cool night air into thetrailer, or a conventional cooler unit may be attached to the outsideair inlet for summer use.

Other objects of the invention are to provide a small, compact heaterthat is readily installed in the available space of a house trailer andwhich is designed so as to avoid over-heating of the relatively closesurrounding surfaces and trailer furnishings; and to provide a heaterconstruction wherein the air has a relatively long travel in contactwith vertically extended heat-- ing surfaces so as to provide ample heatexchange area with a combustion chamber of relatively small transversediameter.

In accomplishing these and other objects of the invention, I haveprovided improved structure, the preferred form of which is illustratedin the accompanying drawing wherein:

, Fig. l is a side elevational view of a heater constructed inaccordance with the present invention, a part of the casing being brokenaway to better illustrate the construction.

Fig. 2 is a plan view.

Fig. 3 is a vertical section through the lower portion of the heatertaken on line 3-3 of Fig. 5.

Fig. 4 is a vertical section on the line 44 of Fig. 2.

Fig. 5 is-ahorizontal section through the lower portion of the heater onthe line 5-5 of Fig. 1.

Fig. 6 is a vertical section through the lower portion of the heatertaken on the line 6-6 of Fig. 4.

Fig. '7 is a vertical section through a heater showing a modified formof construction.

Fig. 8 is a side elevatio-nal view of the heater shown in Fig. 7 withparts broken away and in section.

Refer-ring first to the construction illustrated in Figs. 1 to 6:

designates a heater especially designed for use in heating the interiorspace of a house trailer and which includes an outer casing 2 havingrelatively small width and depth to permit mounting in the relativelysmall space in which such heaters are installed. The casing, however, isof substantially elongated form and extends from the floor to near theceiling of the trailer so as to obtain maximum travel of circulated airin contact with a relatively tall heating unit under pressure effectedby an air circulator unit 3.

The casing 2 includes front and rear walls 45 and side walls 6-4 formedof suitable material. The top of the casing is closed by a cap 8 whichcarries the unit 3 as later described. The lower end of the casing isclosed by a bottom 9 having support on the floor and which mounts a base10 which carries a heating unit generally designated ii that extendsperpendicular within the casing as shown in Fig. 2.

The heating unit includes a combustion chamber [2 of substantial lengthbut of small diameter to provide ample space therearound for acircumferential partition member l3. The partition member I3 issupported on a horizontal partition i4 having an opening through whichthe lower portion of the heater extends. The partition extends upwardlyand terminates below the cap 8 to cooperate with the walls of the outercasing and exterior surfaces of the heater unit to provide inner andouter vertical passageways Hi and H. The bottom of the passageway I! isclosed by the horizontal partition l4 while the upper end isinterconnected with the passageway 16 across the top of the partition 13by a space [8 below the top 8.

The lower portion of the heating unit includes a relatively largercylindrical portion [9 that is joined with the wall of the combustionchamber H to form a burner chamber 20. The base is spaced above thebottom 9 to provide an air passageway 2| having an air inlet opening 22to supply combustion air through an opening 23 to a burner 24.

In the illustrated instance the burner 24 is of the pot type and issupported within the burner chamber by a suitable stand 25 that rests onthe bottom 9. The burner pot seats a fire ring 26 through which productsof combustion pass into the combustion chamber. The diameter of theburner chamber is such that the inner passageway [6 continues to thebottom 9 where it connects with an air duct 21 that is adapted to leadto a hard-to-heat portion of the trailer, for example, the bedroom oraremote end of the trailen The passageways l6 and I! also connect withthe space above the floor of the trailer through louvers 2B and grilles29 that are located in the side walls 6 and 1.

The upper portion of the combustion chamber is connected with a flue 30that extends through an air duct- 3l, the flue being adapted to beconnected to an outlet in the roof of the trailer (not shown). The duct3| includes front, rear and side walls 32, 33, 34 and 34' that areclosed about the flue 30 by a ring 35. The walls of the duct dependwithin the outer casing to a point below the terminal edge 36 of thepartition 13 and surround a conical end of the combustion chamber or aconical cowl 3'1 surrounding the top of the combustion chamber to forman aspirating opening 38 for a purpose later described.

Connected with one of the side walls of the duct 3! is an air circulatorcomprising a blower 39 having a motor 3 for operating the impellerthereof. The blower has an outlet 40 that connects with the duct 3! asindicated in Fig. 1. Air is drawn into the blower through an opening 4!from adjacent the ceiling of the trailer to gather air from the ceilingand effect forced circulation thereof downwardly through the duct 3| andthrough the aspirating opening 38 into the space 4 16 to be heated bycontact with the surfaces of the combustion chamber. The heated air isdischarged under pressure at the bottom of the casing through the grilleopening 29 and through the pipe connection 27 which leads to ahard-toheat point of the trailer.

This method of heating the air maintains very close floor and ceilintemperatures and avoids the unhealthy conditions as above noted, butwhen the house trailer is parked in locations where electricity is notavailable, it is necessary to provide gravity circulation so that theinterior of the trailer may be heated. With gravity circulation it isnecessary to provide an upward circulation of air through the space it,the air being admitted through the grille openings 29. Upon being heatedthe air expands and rises naturally to the top of the passageway whereit is discharged over the top of the partition 53 for discharge into theinterior of the trailer through louvered openings 52.

It is obvious for this method of circulation that a separate outlet mustbe provided for the rising column of air and for this reason it isnecessary to leave the top of the passageway open, otherwise resistanceto flow by the fan and contact of the heated air with the motor wouldrender such method impractical. The open top of the passageway i=3 wouldrender the forced circulation impractical since the resistance todownward flow around the combustion chamber would cause spilling of theair through the open top of the passageway, however, with the aspiratingopening sufficient air is aspirated through the open tops of hepassageways to overcome back pressure on the forced air flow with theresult that all of the forced air passes dovmwardly through thepassageway 58. The aspirated air is obtained by the natural circulationof air through the passageway i7 responsive to expansion of the airbeing heated therein by contact with the outer face of the partition l3.Since air is constantly being admitted to the lower end of thepassageway l'l through the louver openings 28, constant circulation ismaintained upwardly in the passageway H, the air not used and the airnot aspirated being discharged through the louver openings 42. This flowof air through the passageway 17 is also maintained when the heater isoperating under natural gravity circulation and forms an importantvfunction of carrying away heat from the partition 83 to avoidoverheating the walls of the casing.

The burner may be supplied with fuel from a suitable tank 43 mounted onthe back wall of the outer casing and which delivers fuel to an oillevel and regulating valve 44 which is connected with the vaporizer pcttype burner by a pipe 45.

To promote a fresh air condition within the trailer space and preventburning up of the oxy gen in the-air as well as sweating and frosting ofthe windows, it is desirable to provide for admission of fresh air. Thisis eifected by a duct 46 that has an inlet 47 adapted to extend throughan opening in the floor of the trailer and which rises alongside therear wall to terminate in a laterally extending duct 48 dischargin intothe air inlet opening of the blower. When the blower is in operation airis drawn through the supply duct 45 by the aspirating effect of the airdrawn into the inlet opening of the blower under control of a damper 16.

Assuming that the heater is constructed and assembled as describedwithin a trailer and that the burner 24 and blower 38 are in operation,air

is drawn through the inlet of the blower 39' and discharged downwardlythrough the housing- 31 in heatexchange relation with the flue 39 andaround the walls of the combustion chamber to be heated thereby, the hotair being discharged near floor level through the grille 29 and ductconnection 21. Simultaneously air is moving upwardly through thepassageway I? by gravity circulation so as to avoid overheating of thewalls of the outer casing by the heat accumulating in the partition l3.

During operation of the fan, fresh air is being supplied through theduct 45 so as to maintain good atmospheric conditions within the livingspace of the trailer and prevent burnin up of the oxygen in the airincidental to operation of the burner. During this method ofcirculation, air under pressure is prevented from escaping through theopen top of the passageway l by the air that is aspirated downwardlytherethrough. Any of the heated air that does escape through the louveropenings 42 passes into the low pressure area surrounding the blower andis immediately drawn into the blower inlet. It is thus obvious that thisair does not increase ceiling temperatures.

In case an electric supply is not available for actuating the motor ofthe blower, a natural circulation is maintained by air moving reverselythrough the air grilles 28 and 29 up through the spaces l6 and I! inheat exchange relation with the combustion chamber I 2 from where theheated air is discharged into the heating space of the trailer throughthe louvered openings 42.

In the form of the invention shown in Figs. 7 and 8 all parts areenclosed within an outer casing 49 having front, rear and sidewalls 50,5|, 52 and 53, a bottom 54 and a top 55. Located in the casing is aheater unit 56 substantially conforming in construction to the heaterunit previously described. The heater unit, like that of the firstdescribed form, is enclosed by a partition 51 spaced from the walls ofthe heater unit and from the casing to provide vertical passageways 58and 59. The partition 51 terminates short of the top of the outer casingin encircling relation with the flue 60 that extends through the top 55of the casing. Encircling the flu 60 is an air duct 6| having adepending annular flange encircling the flue 69 and providing anaspiratingv passageway 62 in connection with the passage way 59 as bestshown in Fig. 7. The duct 6| is supplied with air that is drawn from theupper portion of the trailer space by a blower 63 contained within ahousing 65', the blower'having an inlet duct 65 opening through the top55 of the casing. The blower-has an outlet connection 66 with the airduct 6| so that the air drawn from near the ceiling of the trailer, byway of the duct 65, is discharged through the duct 6| and downwardlywithin the passageways 59 surrounding the heating unit whereby the airis heated and the heated air is discharged at the bottom of the casingnear the floor through louvers 5'! located in opposite side walls of thecasing. Fresh air is supplied to the blower housing through a duct 68that leads upwardly through the floor of the trailer and connects withthe blower housing as ill indicated at B9. The ducts 65 and 68 may bepro- When the blower is not in operation, a reverse natural gravitycirculation is effected by air that passes into the casing near thefloor through louver 10 located in opposite side walls of the casingfrom where the air passes upwardly along sides of the heater unitthrough the passageways 59 and is discharged over the top of thepartition 5'! through louvers H located in the front and side walls 50,52 and 53 of the casing. Si-

multaneously an air flow is also effected up the outer passageway 58 tocarry away the heat that may pass by radiation to the partition 51. Thenatural circulation is shown by the dotted arrows and theforced aircirculation by the solid arrows. When the blower is in operation, therei an induced fiow of air downwardly through the passageway 59 by theaspirating effect of the air discharged from the blower in substantiallythe same manner as in the first-described construction.

In the spring and fall the burner may be op erated at low heat duringmuggy weather and the dampers l5 and 16 adjusted so'that all of the airis taken in' from the outside and vpassed through the heater for dryingpurposes before discharge into the living space. In the latter form, thefuel supply tank I2 and constant level regulating valve 13 are locatedwithin the casing alongside of the fresh air supply duct and access ishad therethrough through a door 14 located in the side wall 52 of thecasing.

If desired adetachable cooling unit 18 may be attached to the inlet endof the duct 68 and the forced air circulator may be operated to aircondition the interior of the trailer for summer use, or if desired theheat accumulated from the sun's rays during the day time may beeliminated by drawing in the cool night air. In both instances,

the damper 15 will be closed and the damper 16 opened.

From the foregoing it is obvious that I have provided a forced air typeof heater which is especially adapted for use in connection with housetrailers and by reason of the forced air circulation from the ceilingtoward the floor. Consequently, the air in the trailer is maintainedmore nearly uniform, thereby avoiding the unhealthy cold conditions nearthe floor and heat at the ceiling. It is also obvious that when electriccurrent is not available the heater functions satisfactorily by naturalcirculation, the circulation, however, being reverse to that of theforced air circulation.

' What I claim and desire to secure by Letters Patent is:

1. A heater including an upright'casing having side walls and a top, apartition having a closed'cross sectional figure and spaced inwardlyfrom side walls of the casing and terminating short of said top forforming vertical inner and outer flew passageways within the casing.said casing having an opening in the upper por tion thereof incommunication with the upper ends of both of said passageways and havingopenings in the lower portion in connection with the lower ends of saidpassageways for natural gravity circulation upwardly through both ofsaid passageways, a heating unit within the inner flow passageway, and ablower having an inlet ,for air exteriorly of the upper portion of theing spaced inwardly of the terminal of the partition to provide a spacetherebetween for connection with the outer flow passageway for effectingasperation of a part of the air flow from said outer flow passagewaydownwardly through the inner flow passageway when the blower is inoperation.

2. A heater including an upright casing, means forming vertical innerand outer flow passageways within the casing interconnected at theirupper ends, said casing having openings in the lower portion thereof inconnection with lower ends of the inner and outer flow passageways andhaving an opening in the upper portion in communication with both ofsaid passageways at their interconnected upper ends for natural gravitycirculation of air upwardly through both passageways, a heating unitwithin the inner flow passageway to heat said air, a blower housing inthe casing, an inlet duct connected with the blower housing and incommunication with the exterior of the upper end of the casing, adischarge duct connected with the blower housing and having an outletdischarging downwardly into the upper end of the inner flow passageway,and a blower in the blower housing for discharging a jet of air into theinner passageway in reverse movement to the natural air flow, said ductoutlet being of a size relatively to the means forming the innerpassageway to provide a passage therebetween in communication with theouter flow passageway to provide an aspirating effect on the natural airflow from said outer flow passageway to cause downward movement of apart of the air flow into the inner passageway-responsive to said jetwhen the blower is c in operation.

3. A heater including an upright casing, means forming vertical innerand outer flow passageways within the casing interconnected at the upperends thereof, said casing having openings in the lower portion of thecasing in connection with the lower ends of the inner and outer flowpassageways and having an opening in the upper portion in communicationwith both of said passageways at substantially the point ofinterconnection for natural gravity circulation upwardly through thecasing, a heating unit within the inner flow passageway, a blowerhousing in the casing, an inlet duct connected with the blower housingand in communication with the exterior of the upper portion of thecasing, a discharge duct connected with the blower housing and having anoutlet discharging downwardly into the upper end of the inner flowpassageway, a blower in the blower housing for discharging a jet throughthe discharge duct and into the inner passageway, said discharge ductoutlet being of a size relatively to the means forming the innerpassageway to provide a passage therebetween in communication with theouter flow passageway for efiecting asperation of a part of the naturalair flow in said outer passageway by said jet and movement thereofdownwardly through the inner flow passageway when the blower is inoperation, and a fresh air inlet duct connected with the blower housingand extending downwardly of the casing for supplying fresh air to theair circulated downwardly through the inner flow passageway.

4. A heater including an upright casing, means forming vertical innerand outer flow passageways within the casing with said passageways beinginterconnected at their upper ends, said casing having openings in theupper and lower portions thereof in connection with said passagewayswith the upper of said openings being in connection with the upper endsof both inner and outer passageways for natural gravity circulationupwardly through the casing, a heating unit within the inner flowpassageway, a blower housing in the casing, an inlet duct connected withthe blower housing and in communication with the exterior of the upperportion of the casing, a discharge duct connected with the blowerhousing and having an outlet discharging downwardly into the upper endof the inner flow passageway for reversing air flow in the passageway, ablower in the housing, said duct outlet being of a size relatively tothe means forming the inner passageway to provide a passagewaytherebetween in communication with the upper interconnection of the flowpassageway for effecting asperation of a part of the natural air flowfrom said outer flow passageway downwardly of the inner flow passagewaywhen the blower is in operation, a fresh air inlet duct connected withthe blower housing and extending downwardly of the casing for supplyingfresh air to the air circulated downwardly through the inner flowpassageway, and dampers in the blower inlet and fresh air ducts forproportioning ratio of the fresh air and circulated air,

5. A heater including a vertically elongated casing having openings atupper and lower portions thereof, a heating unit within the casing, avertical partition in the casing and surrounding the heating unit tocooperate with the casing and heating unit in forming inner and outervertical flow passageways on respective sides of the partition andinterconnected across the top of the partition, said lower ends of theinner and outer passageways being connected with the lower of the casingopenings and their upper ends having common connection with the upper ofthe casings openings substantially at the interconnection of saidpassageways, an air duct having an outlet discharging downwardly intothe upper end of the inner passageway and of smaller cross section thanthe space defined by said partition and spaced inwardly of the upper endof the partition to provide an aspenating passageway therebetween inconnection with said outer passageway and with said open: ing in theupper portion of the casing, and a blower having an inlet exteriorly ofthe upper portion of the casing for drawing in air and having adischarge connection with said air duct for discharging the air throughthe outlet .of said duct in a jet downwardly through the innerpassageway to said lower opening of the casing and to efiect movement ofair through the asperating passageway and downwardly of the innerpassageway when the blower is in operation.

6. A heater including a vertically elongated casing having openings atupper and lower portions thereof, a heating unit within the casing. avertical partition in the casing and surrounding the heating unit tocooperate with the casing and heating unit in forming inner and outervertical flow passageways on respective sides of the partition andinterconnected across the top of the partition, said lower ends of theinner and outer passageways being connected with the lower of the casingopenings and their upper ends having common connection with the upper ofthe casing openings substantially at the interconnection of saidpassageways, an air duct having an outlet discharging downwardly intothe upper end of the inner passageway and of smaller cross section thanthe space defined by said partition and spaced inwardly of the upper endof the partition to provide an asperating passageway therebetween inconnection with said outer passageway and with said opening in the upperportion of the casing, and a blower having upper and lower inletsexteriorly of the upper and lower portions of the casing for drawing inair and having a discharge connection with said air duct for dischargingthe air through the outlet of said duct in a jet downwardly through theinner passageway to said lower opening of the casing and to effectmovement of air through the asperating passageway and downwardly of theinner passageway when the blower is in operation.

7. A heater including a vertically elongated casing having openings atupper and lower portions thereof, a heating unit within the casing, avertical partition in the casing and surrounding the heating unit tocooperate with the casing and heating unit in forming inner and outervertical flow passageways on respective sides of the partition andinterconnected across the top of the partition, said lower ends of theinner and outer passageways being connected with the lower of the casingopenings and their upper ends having common connection with the upper ofthe casing openings substantially at the interconnection of saidpassageways, an air duct having an outlet discharging downwardly intothe upper end of the inner passageway and of smaller cross section thanthe space defined by said partition and spaced inwardly of the upper endof the partition to provide an asperating passageway therebetween inconnection with said outer passageway and with said opening in the upperportion of the casing, a blower in a housing having upper and lowerinlets exteriorly of the upper and lower portions of the casing fordrawing in air from outside the casing and having a discharge connectionwith said air duct for discharging the air through the outlet of saidduct in a jet downwardly through the inner passageway to said loweropening of the casing and to effect movement of air through theasperating passageway and downwardly of the inner passageway when theblower is in operation, and dampers in said inlets to the blower housing'for controlling ratio of flow through the respective inlets.

8. A heater including a vertically elongated casing having openings atupper and lower portions thereof, a heating unit within the casing, avertical partition in the casing and surrounding the heating unit tocooperate with the casing and heating unit in forming inner and outervertical flow passageways on the respective sides of the partition, saidpassageways being in connection with each other at upper ends thereofand in connection with the upper opening of the casing, said heatingunit being tapered upwardly and inwardly at the upper end of thepartition to provide a funnel-shaped inlet to the inner passageway, anair duct having an outlet discharging downwardly into the funnel-shapedinlet and of smaller cross section than the space defined by saidpartition and spaced inwardly between the upper end of the partition andsaid tapered portion of the heating unit to provide an asperatingpassageway in connection with the outer passageway and surrounding theoutlet of said duct, and a blower having an inlet exteriorly of theupper portion of the casing for drawing in air and having a dischargeconnection with said air duct for discharging said air through theoutlet of said duct in a jet downwardly through the inner passageway toeffect movement of air through the asperating passageway into the innerpassageway when the blower is in operation, said passageways beingconnected with the lower of said housing openings for passage of airinto the lower ends of the inner and outer passageway when the blower isnot in operation and to allow discharge of air from the inner passagewaywhen the blower is in operation.

ELLWOOD E. LITTLE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 926,332 Hunt June 29 19091,169,448 Williams Jan. 25, 1916 2,370,181 Miller Feb. 27, 19452,457,818 Heiman Jan. 4, 1949 2,470,571 Miller May 17, 1949 2,478,069Walter Aug. 2, 1949

